The role of dust formation in the atmospheres of pulsating Red Giant stars
Jan Martin WINTERS
MPI, Bonn
Résumé :
The thermodynamical conditions encountered in the extended atmospheres
of pulsating Asymptotic Giant Branch stars allow for the efficient
formation of small solid particles ('dust grains') out of the gas
phase. Due to their huge photon cross sections, the grains efficiently
transmit energy and momentum from the stellar radiation field to the
atmospheric gas. Thereby, the emerging dust component changes the
local conditions of its own formation. Moreover, the highly non-linear
self-regulating dust formation process also induces important
non-local feedbacks on the hydrodynamical and thermodynamical
structure of the dust forming system, leading to several dynamical
phenomena (such as dust induced shock waves and the existence of an
eigen-timescale of the circumstellar shell) with specific observable
consequences.
In the talk, I will highlight important aspects of the dust formation
process and present corresponding hydrodynamical model calculations,
which will be confronted with observations of dust forming long-period
variable stars.
